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CryptX-0.087_002
⭐ Starred 36 / Crypt::AuthEnc::EAX
Security Advisories (2)
CVE-2026-41564 (2026-04-23)

CryptX versions before 0.088 for Perl do not reseed the Crypt::PK PRNG state after forking. The Crypt::PK::RSA, Crypt::PK::DSA, Crypt::PK::DH, Crypt::PK::ECC, Crypt::PK::Ed25519 and Crypt::PK::X25519 modules seed a per-object PRNG state in their constructors and reuse it without fork detection. A Crypt::PK::* object created before `fork()` shares byte-identical PRNG state with every child process, and any randomized operation they perform can produce identical output, including key generation. Two ECDSA or DSA signatures from different processes are enough to recover the signing private key through nonce-reuse key recovery. This affects preforking services such as the Starman web server, where a Crypt::PK::* object loaded at startup is inherited by every worker process.

CVE-2026-41565 (2026-05-28)

CryptX versions before 0.088_001 for Perl have a stack buffer overflow in four AEAD decrypt_verify helpers. The gcm_decrypt_verify, ccm_decrypt_verify, chacha20poly1305_decrypt_verify and eax_decrypt_verify XS routines copied the caller-supplied authentication tag into a fixed 144-byte stack buffer (MAXBLOCKSIZE) without checking the supplied length. A longer tag overwrites the stack past the buffer. Version 0.088 added the clamp to gcm_decrypt_verify, and 0.088_001 added it to the other three. Any caller of an affected helper that forwards an attacker-controlled tag longer than the buffer can trigger the overflow.

NAME

Crypt::AuthEnc::EAX - Authenticated encryption in EAX mode

SYNOPSIS

### OO interface
use Crypt::AuthEnc::EAX;

# encrypt and authenticate
my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
$ae->adata_add('additional_authenticated_data1');
$ae->adata_add('additional_authenticated_data2');
my $ct = $ae->encrypt_add('data1');
$ct .= $ae->encrypt_add('data2');
$ct .= $ae->encrypt_add('data3');
my $tag = $ae->encrypt_done();

# decrypt and verify
my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
$ae->adata_add('additional_authenticated_data1');
$ae->adata_add('additional_authenticated_data2');
my $pt = $ae->decrypt_add('ciphertext1');
$pt .= $ae->decrypt_add('ciphertext2');
$pt .= $ae->decrypt_add('ciphertext3');
my $tag = $ae->decrypt_done();
die "decrypt failed" unless $tag eq $expected_tag;

#or
my $result = $ae->decrypt_done($expected_tag); # 0 or 1

### functional interface
use Crypt::AuthEnc::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);

my ($ciphertext, $tag) = eax_encrypt_authenticate('AES', $key, $iv, $adata, $plaintext);
my $plaintext = eax_decrypt_verify('AES', $key, $iv, $adata, $ciphertext, $tag);

DESCRIPTION

EAX is a mode that requires a cipher, CTR and OMAC support and provides encryption and authentication. It is initialized with a random IV that can be shared publicly, additional authenticated data which can be fixed and public, and a random secret symmetric key.

EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);

FUNCTIONS

eax_encrypt_authenticate

my ($ciphertext, $tag) = eax_encrypt_authenticate($cipher, $key, $iv, $adata, $plaintext);

# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $iv ...... unique initialization vector (no need to keep it secret)
# $adata ... additional authenticated data

eax_decrypt_verify

my $plaintext = eax_decrypt_verify($cipher, $key, $iv, $adata, $ciphertext, $tag);
# on error returns undef

METHODS

new

my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv);
#or
my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv, $adata);

# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $iv ...... unique initialization vector (no need to keep it secret)
# $adata ... additional authenticated data (optional)

adata_add

$ae->adata_add($adata);                        # can be called multiple times

encrypt_add

$ciphertext = $ae->encrypt_add($data);         # can be called multiple times

encrypt_done

$tag = $ae->encrypt_done();                    # returns $tag value

decrypt_add

$plaintext = $ae->decrypt_add($ciphertext);    # can be called multiple times

decrypt_done

my $tag = $ae->decrypt_done;           # returns $tag value
#or
my $result = $ae->decrypt_done($tag);  # returns 1 (success) or 0 (failure)

clone

my $ae_new = $ae->clone;

SEE ALSO